U.S. patent application number 15/093558 was filed with the patent office on 2016-10-13 for led-based illumination systems having sense and communication capability.
The applicant listed for this patent is Xicato, Inc.. Invention is credited to Gerard Harbers, Warren A. Kartadinata, Barry Mark Loveridge, Martin Emil Mueller, Peter K. Tseng.
Application Number | 20160302280 15/093558 |
Document ID | / |
Family ID | 55808879 |
Filed Date | 2016-10-13 |
United States Patent
Application |
20160302280 |
Kind Code |
A1 |
Harbers; Gerard ; et
al. |
October 13, 2016 |
LED-BASED ILLUMINATION SYSTEMS HAVING SENSE AND COMMUNICATION
CAPABILITY
Abstract
An LED based illumination device includes a plurality of LEDs
that emit light through an output port of a housing. The LED based
illumination device includes a heat sink that is in thermal contact
with the plurality of LEDs. A peripheral electrical circuit board
is configured to be contained within the housing, e.g., surrounding
at least a portion of the heat sink. The peripheral electrical
circuit board may include a radio frequency (RF) transceiver
configured to communicate data between the LED based illumination
device and another electronic device. A primary electrical circuit
board may be electrically coupled to the peripheral electrical
circuit board and electrically coupled to the plurality of
LEDs.
Inventors: |
Harbers; Gerard; (Sunnyvale,
CA) ; Loveridge; Barry Mark; (San Jose, CA) ;
Mueller; Martin Emil; (Fremont, CA) ; Tseng; Peter
K.; (San Jose, CA) ; Kartadinata; Warren A.;
(Fremont, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Xicato, Inc. |
San Jose |
CA |
US |
|
|
Family ID: |
55808879 |
Appl. No.: |
15/093558 |
Filed: |
April 7, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62144846 |
Apr 8, 2015 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F21V 23/006 20130101;
H05B 47/19 20200101; F21V 23/0435 20130101; F21V 7/00 20130101;
F21V 29/70 20150115; H05K 1/0203 20130101; F21V 23/06 20130101;
H05K 1/0274 20130101; H05K 1/181 20130101; F21V 17/10 20130101;
F21Y 2115/10 20160801; F21V 23/0464 20130101; F21Y 2101/00
20130101; H05B 45/10 20200101; F21Y 2105/10 20160801; F21K 9/64
20160801; H05K 2201/10098 20130101; H05K 2201/10151 20130101; H05K
2201/10159 20130101; H05K 2201/10106 20130101 |
International
Class: |
H05B 33/08 20060101
H05B033/08; H05B 37/02 20060101 H05B037/02; F21V 29/70 20060101
F21V029/70; H05K 1/02 20060101 H05K001/02; H05K 1/18 20060101
H05K001/18 |
Claims
1. An LED based illumination device, comprising: a plurality of
LEDs mounted to a top surface of an LED mounting board, wherein the
LED mounting board includes a heat dissipating bottom surface
opposite the top surface of the LED mounting board; a heat sink
disposed below the LED mounting board and in contact with the heat
dissipating bottom surface; a peripheral electrical circuit board
disposed below light emitting surfaces of the plurality of LEDs and
surrounding at least a portion of the heat sink; a primary
electrical circuit board electrically coupled to the peripheral
electrical circuit board and electrically coupled to the LED
mounting board; and a housing configured to capture the LED
mounting board, the heat sink and the peripheral electrical circuit
board.
2. The LED based illumination device of claim 1, wherein the
housing is also configured to capture the primary electrical
circuit board.
3. The LED based illumination device of claim 1, wherein the LED
mounting board is electrically coupled to the primary electrical
circuit board by a plurality of compliant electrical contact
elements.
4. The LED based illumination device of claim 1, wherein a radio
frequency transmitter is coupled to the peripheral electrical
circuit board.
5. The LED based illumination device of claim 1, wherein a radio
frequency transceiver is coupled to the peripheral electrical
circuit board.
6. The LED based illumination device of claim 5, wherein the
peripheral electrical circuit board includes an antenna coupled to
the radio frequency transceiver.
7. The LED based illumination device of claim 5, wherein the
housing includes an antenna coupled to the radio frequency
transceiver.
8. The LED based illumination device of claim 1, wherein the
peripheral electrical circuit board includes a sensor element
exposed to an amount of light emitted from the LED based
illumination device.
9. The LED based illumination device of claim 1, wherein a sensor
element exposed to an environment illuminated by the LED based
illumination device is communicatively coupled to the peripheral
electrical circuit board.
10. The LED based illumination device of claim 9, wherein a command
signal that causes a change in a luminous output of the LED based
illumination device is determined based at least in part on a
sensor signal received from the sensor element.
11. The LED based illumination device of claim 9, wherein the
sensor element is an optical sensor.
12. The LED based illumination device of claim 1, wherein the LED
mounting board includes a sensor element exposed to an amount of
light emitted from the LED based illumination device.
13. The LED based illumination device of claim 1, wherein the
primary electrical circuit board supplies electrical current to the
plurality of LEDs.
14. The LED based illumination device of claim 1, wherein the LED
mounting board includes an amount of memory.
15. An LED based illumination device, comprising: a housing
configured to capture an LED based light engine that includes a
plurality of LEDs mounted to an LED mounting board, wherein an
amount of light emitted by the LED based light engine passes
through an output port of the housing, wherein the housing is
configured to be attachable to a heat sink such that a bottom
surface of the LED mounting board is in contact with the heat sink
when the housing is attached to the heat sink; a peripheral
electrical circuit board configured to be captured by the housing,
wherein the peripheral electrical circuit board includes a radio
frequency (RF) transceiver configured to communicate data between
the LED based illumination device and another electronic
device.
16. The LED based illumination device of claim 15, further
comprising: an antenna disposed on the peripheral electrical
circuit board and electrically coupled to the RF transceiver.
17. The LED based illumination device of claim 15, further
comprising: an antenna disposed on the housing and electrically
coupled to the RF transceiver.
18. The LED based illumination device of claim 15, further
comprising: a primary electrical circuit board electrically coupled
to the LED based light engine and the peripheral electrical circuit
board, wherein the primary electrical circuit board is configured
to supply electrical current to the plurality of LEDs.
19. The LED based illumination device of claim 18, wherein the RF
transceiver of the peripheral electrical circuit board is
configured to communicate an amount of diagnostic data received
from the primary electrical circuit board.
20. The LED based illumination device of claim 18, wherein the
primary electrical circuit board includes an LED driver configured
to supply the electrical current to the plurality of LEDs based on
a command signal received from the peripheral electrical circuit
board.
21. The LED based illumination device of claim 20, wherein the
peripheral electrical circuit board includes a processor configured
to determine the command signal based on a sensor signal received
from a sensor mounted to the peripheral electrical circuit
board.
22. The LED based illumination device of claim 21, wherein the
sensor is any of a temperature sensor, a humidity sensor, an
optical sensor, a pressure sensor, a vibration sensor, and an
orientation sensor.
23. The LED based illumination device of claim 20, wherein the
peripheral electrical circuit board includes a processor configured
to determine the command signal based on a sensor signal received
from a sensor mounted to the LED based light engine.
24. The LED based illumination device of claim 20, wherein the
peripheral electrical circuit board includes a processor configured
to determine the command signal based on a sensor signal received
from a sensor mounted to a reflector coupled to the LED based light
engine.
25. The LED based illumination device of claim 24, wherein the
sensor is any of a temperature sensor, a humidity sensor, an
optical sensor, a pressure sensor, a vibration sensor, and an
orientation sensor.
26. A light control and data interface module comprising: a primary
electrical circuit board couplable to an electrical power supply
and an LED based light engine, the primary electrical circuit board
configured to receive an amount of electrical power from the
electrical power supply and supply electrical current to the LED
based light engine; and a peripheral electrical circuit board
coupled to the primary electrical circuit board, wherein the
primary electrical circuit board is configured to supply electrical
power to the peripheral electrical circuit board, and wherein the
peripheral electrical circuit board includes a radio frequency (RF)
transceiver configured to communicate data to an external
electronic device.
27. The light control and data interface module of claim 26,
wherein the peripheral electrical circuit board includes: a
processor; and a non-transitory, computer readable medium storing
instructions that when executed by the processor cause the
peripheral electrical circuit board to: receive a control signal on
a first input node; determine a desired luminous output of the LED
based light engine based on the control signal; and transmit a
command signal to a direct current to direct current (DC/DC) power
converter mounted to the primary electrical circuit board, wherein
the DC/DC power converter is configured to supply the electrical
current to the LED based light engine.
28. The light control and data interface module of claim 27,
wherein the control signal adheres to any of a Digital Addressable
Lighting Interface (DALI) standard, a DMX standard, and a 0-10 Volt
standard.
29. The light control and data interface module of claim 26,
wherein the peripheral electrical circuit board includes: a
processor; and a non-transitory, computer readable medium storing
instructions that when executed by the processor cause the
peripheral electrical circuit board to: receive a sensor signal on
a first input node; determine a desired luminous output of the LED
based light engine based on the sensor signal; and transmit a
command signal to a direct current to direct current (DC/DC) power
converter mounted to the primary electrical circuit board, wherein
the DC/DC power converter is configured to supply the electrical
current to the LED based light engine.
30. The light control and data interface module of claim 29,
wherein the sensor signal is received from a sensor coupled a
reflector mounted to the LED based light engine.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 USC 119 to U.S.
Provisional Application No. 62/144,846, filed Apr. 8, 2015, which
is incorporated by reference herein in its entirety.
TECHNICAL FIELD
[0002] The described embodiments relate to illumination devices
that include Light Emitting Diodes (LEDs).
BACKGROUND
[0003] The use of LEDs in general lighting is becoming more
desirable and prevalent. Typically, LED illumination devices are
standalone units. It is desirable, however, to collect data with
LED illumination devices and to be able to communicate that data to
external devices.
SUMMARY
[0004] An LED based illumination device includes a plurality of
LEDs that emit light through an output port of a housing. The LED
based illumination device includes a heat sink that is in thermal
contact with the plurality of LEDs. A peripheral electrical circuit
board is configured to be contained within the housing, e.g.,
surrounding at least a portion of the heat sink. The peripheral
electrical circuit board may include a radio frequency (RF)
transceiver configured to communicate data between the LED based
illumination device and another electronic device. A primary
electrical circuit board may be electrically coupled to the
peripheral electrical circuit board and electrically coupled to the
plurality of LEDs.
[0005] In one implementation, an LED based illumination device
includes a plurality of LEDs mounted to a top surface of an LED
mounting board, wherein the LED mounting board includes a heat
dissipating bottom surface opposite the top surface of the LED
mounting board; a heat sink disposed below the LED mounting board
and in contact with the heat dissipating bottom surface; a
peripheral electrical circuit board disposed below light emitting
surfaces of the plurality of LEDs and surrounding at least a
portion of the heat sink; a primary electrical circuit board
electrically coupled to the peripheral electrical circuit board and
electrically coupled to the LED mounting board; and a housing
configured to capture the LED mounting board, the heat sink and the
peripheral electrical circuit board.
[0006] In one implementation, an LED based illumination device
includes a housing configured to capture an LED based light engine
that includes a plurality of LEDs mounted to an LED mounting board,
wherein an amount of light emitted by the LED based light engine
passes through an output port of the housing, wherein the housing
is configured to be attachable to a heat sink such that a bottom
surface of the LED mounting board is in contact with the heat sink
when the housing is attached to the heat sink; a peripheral
electrical circuit board configured to be captured by the housing,
wherein the peripheral electrical circuit board includes a radio
frequency (RF) transceiver configured to communicate data between
the LED based illumination device and another electronic
device.
[0007] In one implementation, a light control and data interface
module includes a primary electrical circuit board coupleable to an
electrical power supply and an LED based light engine, the primary
electrical circuit board configured to receive an amount of
electrical power from the electrical power supply and supply
electrical current to the LED based light engine; and a peripheral
electrical circuit board coupled to the primary electrical circuit
board, wherein the primary electrical circuit board is configured
to supply electrical power to the peripheral electrical circuit
board, and wherein the peripheral electrical circuit board includes
a radio frequency (RF) transceiver configured to communicate data
to an external electronic device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 depicts an LED based illumination device that
includes a Light Control and Data Interface Module (LCDIM), in an
exemplary, non-limiting embodiment.
[0009] FIGS. 2 and 3 depict a top view and a side view,
respectively, of an LED based illumination device including a
LCDIM.
[0010] FIG. 4 depicts an exploded view illustrating components of
LED based illumination device as depicted in FIGS. 2-3.
[0011] FIG. 5 depicts a bottom perspective view of the housing and
LED based light engine and shows compliant contacts configured to
electrically couple a primary electrical circuit board and the LED
based light engine.
[0012] FIG. 6 depict top perspective view of the primary electrical
circuit board and LED based light engine and shows the compliant
contacts configured to electrically couple the primary electrical
circuit board and the LED based light engine.
[0013] FIG. 7 depicts the primary electrical circuit board fixed to
a mounting plate and surrounding the heat sink.
[0014] FIG. 8 is similar to FIG. 7 and depicts a peripheral
electrical circuit board fixed to the heat sink.
[0015] FIG. 9 depicts an LED based light engine including a one or
more LED die or packaged LEDs and a mounting board to which LED die
or packaged LEDs are attached.
[0016] FIG. 10 depicts a cross-sectional illustration of the LED
based illumination device including optical sensors located on the
LED based light engine outside the light conversion cavity.
[0017] FIG. 11 depicts a cross-sectional illustration of the LED
based illumination device including sensors that are directly
coupled to peripheral electrical circuit board and exposed to the
environment through voids in the housing.
[0018] FIG. 12 depicts a cross-sectional illustration of the LED
based illumination device including a detachably mounted reflector
assembly including sensing capability.
[0019] FIG. 13 depicts a perspective view of a luminaire including
an LED based illumination device with a rectangular form
factor.
[0020] FIG. 14 depicts a perspective view of a luminaire including
an LED based illumination device with a circular form factor.
[0021] FIG. 15 depicts a side view of a luminaire including an LED
based illumination device integrated into a retrofit lamp
device.
DETAILED DESCRIPTION
[0022] Reference will now be made in detail to background examples
and some embodiments of the invention, examples of which are
illustrated in the accompanying drawings.
[0023] FIG. 1 depicts an LED based illumination device 100 in an
exemplary, non-limiting embodiment. LED based illumination device
100 includes a Light Control and Data Interface Module (LCDIM) 110
configured to supply electrical power to an LED based light engine
160. In addition, LCDIM 110 also integrates light control, power
conversion, data acquisition, data processing, and communication
capability.
[0024] In the embodiment depicted in FIG. 1, LCDIM 110 includes a
primary electrical circuit board (ECB) 120 that includes an LED
driver 121 and a peripheral ECB 130 that includes communication
capability such as wireless transceiver 135, which may be a radio
frequency transceiver. In this manner, heat generated by LED driver
121 may be effectively dissipated by locating the primary ECB 120
in close proximity to a heat sink, while sensors and communication
components located on peripheral ECB 130 may be located further
from the heat sink and closer to the environment being used as a
communication medium (e.g., free space around LCDIM 110).
[0025] FIGS. 2 and 3 depict a top view and a side view,
respectively, of an LED based illumination device 200 including a
LCDIM. An example of such a lighting device is the Xicato
Intelligent Module (XIM) manufactured by Xicato, Inc., San Jose,
Calif. (USA).
[0026] FIG. 4 depicts an exploded view illustrating components of
LED based illumination device 200 as depicted in FIGS. 2-3. As
depicted in FIG. 4, LED based illumination device 200 includes LED
based light engine 160, LCDIM 110, including primary ECB 120 and
peripheral ECB 130, heat sink 101, mounting plate 102, with a
primary ECB 120 support 104, and housing 103.
[0027] The assembled LED based illumination device 200 mechanically
integrates the LED based light engine with the LCDIM within a
common housing. However, in general, one or more components of LED
based illumination device 200 may be mechanically separated from
the others. In these embodiments, one or more components may be
separately located on a light fixture and electrically coupled to
the other components by suitable wiring and connectors. In some
embodiments, LED based light engine 160 is assembled within a
simple housing to facilitate attachment to a heat sink. An example
of such a lighting device is the Xicato Thin Module (XTM)
manufactured by Xicato, Inc., San Jose, Calif. (USA). In this
example, one or more components of LCDIM 110 are packaged in a
separate housing, and this assembly is electrically coupled to the
LED based light engine by a wired connection. In some other
embodiments, LED based light engine 160 is assembled with the
primary ECB 120 within a shared housing to facilitate attachment to
a heat sink. The peripheral ECB 130 is packaged in a separate
housing, and this assembly is electrically coupled to the LED based
light engine 160 and the primary ECB 120 by a wired connection. In
some other embodiments, LED based light engine 160 is assembled
with the peripheral ECB 130 within a shared housing to facilitate
attachment to a heat sink. The primary ECB 120 is packaged in a
separate housing, and this assembly is electrically coupled to the
LED based light engine 160 and the peripheral ECB 130 by a wired
connection. In some other embodiments, LED based light engine 160,
the peripheral ECB 130, and the primary ECB 120 are all packaged in
separate housings and are electrically coupled together by a wired
connection.
[0028] It should be understood that as defined herein an LED based
illumination device is not an LED, but is an LED light source or
fixture or component part of an LED light source or fixture. As
depicted in FIGS. 2-8, LED based illumination device 200 includes
an LED based light engine 160 configured to generate an amount of
light. LED based light engine 160 is coupled to heat sink 101 to
promote heat extraction from LED based light engine 160. FIG. 5
depicts a bottom perspective view of the housing 103 and LED based
light engine 160 and shows compliant contacts configured to
electrically couple a primary electrical circuit board and the LED
based light engine. FIG. 6 depict top perspective view of the
primary electrical circuit board 120 and LED based light engine 160
and shows the compliant contacts configured to electrically couple
the primary electrical circuit board and the LED based light
engine. FIG. 7 depicts the primary electrical circuit board 120
fixed to a mounting plate 102 and surrounding the heat sink 101.
FIG. 8 is similar to FIG. 7 and depicts a peripheral electrical
circuit board 130 fixed to the heat sink 101. Primary ECB 120 and
peripheral ECB 130 are shaped to fit around heat sink 101. LED
based light engine 160, primary ECB 120, peripheral ECB 130, and
heat sink 101 are enclosed between mounting plate 102 and housing
103. As illustrated in FIG. 4, the heat sink 101 and mounting plate
102 may be integrally coupled, e.g., manufactured from the same
piece of material. If desired, however, heat sink 101 and mounting
plate 102 may be separate manufactured and heat sink 101 mounted to
mounting plate 102. An optional reflector retainer (not shown) is
coupled to housing 103. The reflector retainer is configured to
facilitate attachment of different reflectors to the LED based
illumination device 200.
[0029] It is advantageous to separate the electronic functionality
of LCDIM 110 across two or more electrical circuit boards, as
depicted in FIGS. 2-8, to minimize logistical complexity. For
example, in a network of LED based illumination devices, certain
devices may include different functionality than others. Common
functionality is included on the primary ECB associated with each
device. In this manner each manufactured device includes the same
primary ECB. However, differing functionality is included in a
different peripheral ECB. In this manner, one or more different
devices may include different peripheral ECBs. For example, a
peripheral ECB associated with one LED based illumination device
may include digital addressable lighting interface (DALI) master
functionality and a peripheral ECB associated with another LED
based illumination device may not include DALI master
functionality.
[0030] Many different configurations may be contemplated, however,
in general, the electronic functionality of LCDIM 110 as described
herein may be distributed across the primary ECB and the peripheral
ECB in any suitable manner.
[0031] In the embodiment depicted in FIG. 1, LED driver 121 of
primary ECB 120 is configured to supply power to one or more LEDs
of the LED based light engine 160 over a wired connection 124
between primary ECB 120 and LED based light engine 160. In one
embodiment, LED driver 121 is a direct current to direct current
(DC/DC) power converter. The DC/DC power converter receives
electrical power signals 111 (e.g., 48 Volt supply voltage)
supplied to primary ECB 120. The electrical power signals 111 are
processed by the DC/DC power converter to generate current signals
125 supplied to the LEDs of LED based light engine 160. In some
other embodiments, LED driver 121 is configured as an AC/DC power
converter configured to convert AC input power signals to DC
current signals supplied to the LEDs of LED based light engine 160.
In some other embodiments, LED driver 121 is configured as an AC/AC
power converter configured to convert AC input power signals to AC
current signals supplied to the LEDs of LED based light engine 160
(e.g., when LED based light engine 160 includes AC LEDs).
[0032] In another aspect, LED based illumination device 200
includes compliant electrical contact elements configured to
electrically couple LED based light engine 160 to primary ECB 120.
Compliant contact elements include formed, elastic, metal contacts
that are assembled within LED based illumination device 200 with an
interference fit that deforms the elastic, metal contacts and
ensures a consistent electrical contact. FIGS. 5-6 depict compliant
contacts 122A-D configured to electrically couple primary ECB 120
and LED based light engine 160 in one embodiment. In the depicted
embodiment, LED based light engine 160 and compliant contacts
122A-D are mounted to housing 103. Housing 103 is disposed over
heat sink 101 and mechanically coupled to heat sink 101 with a
removeable fastener (e.g., screws) or a press fit feature.
Fastening housing 103 to heat sink 101 brings compliant contacts
122A-D into mechanical and electrical contact with primary ECB 120.
As depicted in FIGS. 5-6, compliant contacts 122A-D extend from LED
based light engine 160 in a direction approximately parallel to the
light emitting surface of LED based light engine 160. The compliant
contacts 122A-D are then formed with a ninety degree bend such that
they continue to extend approximately perpendicular to the light
emitting surface of LED based light engine 160 toward the surface
of primary ECB 120.
[0033] FIG. 7 depicts primary ECB 120 fixed to mounting plate 102
and surrounding heat sink 101. Primary ECB 120 includes a connector
141 configured to be coupled to an external electronic device such
as a power supply (e.g., 48 Volt power supply, low voltage power
supply, control gear, network infrastructure, external sensors,
etc.). In addition, a connector 140 is employed to couple primary
ECB 120 and peripheral ECB 130. Primary ECB 120 includes a portion
of connector 140 and peripheral ECB 130 includes a mating portion
of connector 140. In this manner, connector 140 is employed to
electically couple primary ECB 120 to peripheral ECB 130 upon
assembly as depicted in FIG. 8. Peripheral ECB 130 also includes
connector 142 configured to be coupled to an external electronic
device such as a power supply (e.g., 48 Volt power supply, low
voltage power supply, control gear, network infrastructure,
external sensors, etc.).
[0034] In another aspect, as illustrated in FIG. 1, primary ECB 120
includes a power converter 123 configured to supply low voltage
electrical power signals 129 to peripheral ECB 130. In this manner,
electrical power signals 111 can be used to supply electrical power
to LED driver 121 and electrical power to peripheral ECB 130 after
power conversion by power converter 123. In some embodiments, power
converter 123 is a DC/DC power converter that steps down the
voltage of electrical signals 111 to a low voltage range (e.g.,
less than five volts) suitable for powering the electronic
circuitry of peripheral ECB 130. In some embodiments, peripheral
ECB 130 may have a separate power converter. In addition, the power
converter on peripheral ECB 130 may be used to supply low voltage
(e.g., less than five volts) power to the circuitry on the primary
ECB 120.
[0035] In yet another aspect, peripheral ECB 130 includes a
wireless communications interface. In some embodiments the wireless
communications interface is configured to transmit and receive
communications or control signals 137 to and from the peripheral
ECB 130. The wireless communications interface includes a wireless
transceiver 135 operable in accordance with a wireless
communications protocol, and one or more associated antennas 136
mounted to LED based illumination device 100. The wireless
transceiver 135 may be a radio frequency transceiver 135.
Additionally, while a transceiver 135 is described, it should be
understood that the wireless transceiver 135 may be a wireless
receiver, a wireless transmitter or both a wireless receiver and
wireless transmitter. Any suitable wireless communications protocol
may be contemplated, (e.g., Bluetooth, 802.11, Zigbee, cellular
modem, etc.). In some embodiments, the wireless communications
interface is configured to transmit communication signals from the
peripheral ECB 130. The wireless communications interface includes
a wireless transmitter operable in accordance with a wireless
communications protocol, and one or more associated antennas
mounted to LED based illumination device 100. In one example, a
wireless transmitter operable in accordance with an iBeacon
protocol may be employed to broadcast location information.
[0036] In some embodiments, one or more antennas are mounted to the
external facing surface(s) of LED based illumination device 100 to
maximize communication efficiency between LED based illumination
device 100 and a remotely located communications device (e.g.,
router, mobile phone, or other computing system). In some
embodiments, an antenna is integrated into the peripheral ECB 130.
In some other embodiments, the antenna is integrated into the
primary ECB 120. In some other embodiments, the antenna is
integrated into housing 103, for example, by molding the antenna
into the housing structure or attaching the antenna to a surface of
the housing structure. In some other embodiments, the antenna is
integrated into the mounting board of the LED based light engine
160.
[0037] As depicted in FIG. 1, primary ECB 120 includes an internal
communications bus 128 coupled to various components of primary ECB
120 including processor 122, memory 126, digital interface 127,
power converter 123, and LED driver 121. Similarly, peripheral ECB
130 includes an interal communications bus 134 coupled to various
components of peripheral ECB 130 including processor 132, memory
133, digital interface 131, and transceiver 135.
[0038] In a further aspect, any of memory 126 of primary ECB 120
and memory 133 of peripheral ECB 130 stores identification data,
operational data such as temperature history, current history, etc.
For example, an identification number, a network security key,
commissioning information, etc. may be stored on either, or both of
these memories.
[0039] In another further aspect, peripheral ECB 130 includes
processor readable instructions stored on memory 133 that cause
processor 132 to receive data 139 from primary ECB 120 and
wirelessly communicate this data from LED based illumination device
100 over transceiver 135. In this manner, processor 132 on board
peripheral ECB 130 aggregates information collected by primary ECB
120 and provides control over the communication of this information
from LED based illumination device 100 to an external electronic
device (e.g., building management server, portable electronic
device such as a mobile phone or tablet computer, etc.). By way of
non-limiting example, data 139 may include temperature data,
electrical performance data, optical performance data,
identification data such as a serial number, etc.
[0040] In another further aspect, peripheral ECB 130 includes
processor readable instructions stored on memory 133 that cause
processor 132 to receive sensor signals (e.g., sensor signals 146)
from any number of sensors coupled to LED based illumination device
100 and wireles sly communicate the collected data from LED based
illumination device 100 over transceiver 135. In some embodiments,
the peripheral ECB 130 may communicate the collected data from LED
based illumination device 100 using wired based communication
interfaces--e.g., Ethernet, PLC, etc. In this manner, processor 132
on board peripheral ECB 130 aggregates information collected by LED
based illumination device 100 and provides control over the
communication of this information from LED based illumination
device 100 to an external electronic device (e.g., building
management server, portable electronic device such as a mobile
phone or tablet computer, etc.).
[0041] As depicted in FIG. 1, sensor signals 146 from LED based
light engine 160 are received by peripheral ECB 130. By way of
non-limiting example, sensor signals 146 may include a serial
number stored in a memory on board LED based light engine 160,
temperature data, flux data, etc.
[0042] In general, sensor signals received by peripheral ECB 130
may originate from a sensor directly coupled to peripheral ECB 130,
a sensor coupled to LED based light engine 160, a sensor coupled to
reflector 150, an external sensor electrically coupled to
peripheral ECB 130, a sensor coupled to primary ECB 120, a sensor
signal coming in over a wireless channel, or any combination of
these sensors.
[0043] Many different types of sensors may be coupled to LED based
illumination device 100. By way of non-limiting example, one or
more occupancy sensors, ambient light sensors, temperature sensors,
cameras, microphones, visual indicators such as low power LEDs,
ultrasonic sensors, vibration sensors, pressure sensors,
orientation sensors, and photodetectors may be coupled to LED based
illumination device 100 and configured to communicate signals to
peripheral ECB 130.
[0044] In some embodiments, it is desireable to locate sensors in
areas that are exposed to ambient light of the environment. While
these sensors may be exposed to light emitted from the LED based
light engine 160, as well, these signals may be seperated in the
time domain or through the use of optical filters, such as filters
that filter infrared or ultraviolet light, which the LEDs may not
produce. FIG. 10 depicts a cross-sectional illustration of LED
based illumination device 210 including optical sensors 180 and 181
located on LED based light engine 160 outside the light conversion
cavity. In some other examples, a sensor (e.g., silicon photo
diode) is located within the light conversion cavity. FIG. 11
depicts a cross-sectional illustration of LED based illumination
device 220 including sensors 190 and 191 that are directly coupled
to peripheral ECB 130 and exposed to the environment through voids
in housing 103.
[0045] In some other examples, sensors may be mounted to a
reflector assembly that is electrically coupled to peripheral ECB
130 (e.g., via an electrical connector, contacts, or inductively
coupled).
[0046] FIG. 12 depicts a reflector assembly including sensing
capability detachably mounted to LED based illumination device 200
in one embodiment. The reflector housing includes a reflector 201,
sensors 204, and an electronics interface board 213. In the
depicted embodiment, the reflector housing includes an outward
facing surface. In other words, at least one surface of the
reflector housing faces away from the light source of LED based
illumination device 200 and toward the environment illuminated by
LED based illumination device 200. Sensors (e.g., sensor 204) are
mounted in the reflector housing along the outward facing surface.
In this manner, the sensors are sensitive to physical signals
directed toward LED based illumination device 200. Signals
generated by the sensors are communicated to an electrical
interface board 213 coupled to the reflector housing for further
processing and communication to LED based illumination device
200.
[0047] Reflector 201 includes an input port configured to receive a
first amount of light emitted from the LED based illumination
device 200 and an output port through which light passes toward the
environment. The reflecting surface(s) of reflector 201 are
configured to redirect at least a portion of the light emitted from
the LED based illumination device toward the output port.
[0048] The reflector assembly is communicatively coupled to
peripheral ECB 130 of LED based illumination device 200 by a
connector 220, and the reflector assembly is configured to transmit
and receive communications signals to and from the peripheral ECB
130. In one embodiment, the electronics interface board 213 is
configured to route communications between the sensor 204 and the
LED based illumination device 200 over a wired interface, such as a
four pin interface including two power pins and two communication
pins (e.g. I2C interface). In some other embodiments, electrical
interface board 213 includes a coiled conductor and peripheral ECB
130 includes a complementary coiled conductor. The conductors are
configured to form an inductive coupling operable in accordance
with a near field communications (NFC) protocol. In this manner,
signals and power may be passed between the reflector assembly and
LED based illumination device 200.
[0049] Many different types of sensors may be mounted to the
reflector assembly. By way of non-limiting example, one or more
occupancy sensors, ambient light sensors, temperature sensors,
cameras, microphones, visual indicators such as low power LEDs,
ultrasonic sensors, vibration sensors, pressure sensors,
orientation sensors, and photodetectors may be mounted to the
reflector assembly.
[0050] In some embodiments, additional sensors may be electrically
coupled to the reflector assembly and data signals 211 generated by
these external sensors are communicated to the electronic interface
board 213. The collected data may then be communicated to LED based
illumination device 200 as described hereinbefore.
[0051] In general, any outwardly facing surface of LED based
illumination device is suitable for any sensor collecting data from
the ambient light in the environment illuminated by LED based
illumination device. However, in some embodiments, one or more
sensors may be located in areas of the LED based illumination
device that are not necessarily exposed to the environment
illuminated by LED based illumination device. For example, one or
more temperature sensors, vibration sensors, and pressure sensors
may coupled to peripheral ECB 130 or primary ECB 120 to monitor
environmental parameters such as temperature, etc., near LED based
illumination device. For example, a temperature sensor may be
mounted close to electronic components of peripheral ECB 130 to
monitor operating temperatures to minimize component failure.
[0052] In another further aspect, as illustrated in FIG. 1,
peripheral ECB 130 includes processor readable instructions stored
on memory 133 that cause processor 132 to receive a control signal
112, determine a desired luminous output of the LED based
illumination device based on the control signal, and transmit a
command signal 138 to the primary ECB 120 to change the luminous
output of the LED based illumination device. In this manner,
processor 132 on board peripheral ECB 130 provides control over the
light emitted from the LED based illumination device 100.
[0053] In some embodiments, control signal 112 is an analog control
signal such as a control signal adhering to a 0-10 Volt standard.
In some other embodiments, control signal 112 is a digital signal
such as a control signal adhering to a Digital Addressable Lighting
Interface (DALI) standard, a DMX standard, Ecosystem.RTM. by
Lutron, Inc., etc.
[0054] In another further aspect, peripheral ECB 130 includes
processor readable instructions stored on memory 133 that cause
processor 132 to receive a control signal 137 received by
transceiver 135, determine a desired luminous output of the LED
based illumination device based on the control signal, and transmit
a command signal 138 to the primary ECB 120 to change the luminous
output of the LED based illumination device.
[0055] In another further aspect, command signal 138 determined by
processor 132 is based on sensor signals received from a sensor
coupled to the peripheral ECB 130, a sensor coupled to LED based
light engine 160, a sensor coupled to reflector 150, an external
sensor electrically coupled to peripheral ECB 130, a sensor coupled
to primary ECB 120, or any combination of these sensors.
[0056] In yet another further aspect, peripheral ECB 130 is
configured to supply power signals 144 to a plurality of sensors
coupled to peripheral ECB 130. In some embodiments, an inductive
coupling between peripheral ECB 130 is further configured to
transmit electrical power to the reflector assembly. In some
examples, up to five Watts of electrical power may be transmitted
in this manner.
[0057] In yet another further aspect, as illustrated in FIG. 12,
the electrical interface board 213 includes a power bus configured
to supply power to the plurality of sensors coupled to the
reflector housing. In this manner, electrical interface board 213
acts as a power supply to sensors attached to the reflector
assembly.
[0058] In yet another aspect, the reflector of the reflector
assembly is removably coupled to the reflector housing. As depicted
in FIG. 12, reflector 201 includes engaging features that allow for
selective attachment and detachment of reflector 201. In this
manner, different reflector shapes can be interchangeably located
within the reflector housing to satisfy particular optical
requirements.
[0059] In some embodiments, as illustrated in FIG. 1, peripheral
ECB 130 includes a Power Line Communication (PLC) module 145
operable to receive an electrical power signal (e.g., signal 111)
and decode a communication signal from the electrical power signal.
Similarly, the PLC module is operable to transmit an electrical
power signal that includes a communication signal component. These
communication signals may be employed to control the light output
of the LED based illumination device and communicate information
between the LED based illumination device and an external
electronic device.
[0060] FIG. 9 is illustrative of LED based light engine 160 in one
embodiment. LED based light engine 160 includes one or more LED die
or packaged LEDs and a mounting board to which LED die or packaged
LEDs are attached. In addition, LED based light engine 160 includes
one or more transmissive elements (e.g., windows or sidewalls)
coated or impregnated with one or more wavelength converting
materials to achieve light emission at a desired color point.
[0061] As illustrated in FIG. 9, LED based light engine 160
includes a number of LEDs 162A-F mounted to mounting board 164 in a
chip on board (COB) configuration. The spaces between each LED are
filled with a reflective material 176 (e.g., a white silicone
material). In addition, a dam of reflective material 175 surrounds
the LEDs 162 and supports transmissive element 174, which may be,
e.g., a plate. The space between LEDs 162 and transmissive element
174 is filled with an encapsulating optically translucent material
177 (e.g., silicone) to promote light extraction from LEDs 162 and
to separate LEDs 162 from the environment. In the depicted
embodiment, the dam of reflective material 175 is both the
thermally conductive structure that conducts heat from transmissive
element 174 to LED mounting board 164 and the optically reflective
structure that reflects incident light from LEDs 162 toward
transmissive element 174.
[0062] LEDs 162 can emit different or the same colors, either by
direct emission or by phosphor conversion, e.g., where phosphor
layers are applied to the LEDs as part of the LED package. The
illumination device 100 may use any combination of colored LEDs
162, such as red, green, blue, ultraviolet, amber, or cyan, or the
LEDs 162 may all produce the same color light. Some or all of the
LEDs 162 may produce white light. In addition, the LEDs 162 may
emit polarized light or non-polarized light and LED based
illumination device 100 may use any combination of polarized or
non-polarized LEDs. In some embodiments, LEDs 162 emit either blue
or UV light because of the efficiency of LEDs emitting in these
wavelength ranges. The light emitted from the illumination device
100 has a desired color when LEDs 162 are used in combination with
wavelength converting materials on transmissive element 174, for
example. By tuning the chemical and/or physical (such as thickness
and concentration) properties of the wavelength converting
materials and the geometric properties of the coatings on the
surface of transmissive element 174, specific color properties of
light output by LED based illumination device 100 may be specified,
e.g., color point, color temperature, and color rendering index
(CRI).
[0063] For purposes of this patent document, a wavelength
converting material is any single chemical compound or mixture of
different chemical compounds that performs a color conversion
function, e.g., absorbs an amount of light of one peak wavelength,
and in response, emits an amount of light at another peak
wavelength.
[0064] By way of example, phosphors may be chosen from the set
denoted by the following chemical formulas: Y3Al5O12:Ce, (also
known as YAG:Ce, or simply YAG) (Y,Gd)3Al5O12:Ce, CaS:Eu, SrS:Eu,
SrGa2S4:Eu, Ca3(Sc,Mg)2Si3O12:Ce, Ca3Sc2Si3O12:Ce, Ca3Sc2O4:Ce,
Ba3Si6O12N2:Eu, (Sr,Ca)AlSiN3:Eu, CaAlSiN3:Eu, CaAlSi(ON)3:Eu,
Ba2SiO4:Eu, Sr2SiO4:Eu, Ca2SiO4:Eu, CaSc2O4:Ce, CaSi2O2N2:Eu,
SrSi2O2N2:Eu, BaSi2O2N2:Eu, Ca5(PO4)3Cl:Eu, Ba5(PO4)3Cl:Eu,
Cs2CaP2O7, Cs2SrP2O7, Lu3Al5O12:Ce, Ca8Mg(SiO4)4Cl2:Eu,
Sr8Mg(SiO4)4Cl2:Eu, La3Si6N11:Ce, Y3Ga5O12:Ce, Gd3Ga5O12:Ce,
Tb3Al5O12:Ce, Tb3Ga5O12:Ce, and Lu3Ga5O12:Ce.
[0065] In one example, the adjustment of color point of the
illumination device may be accomplished by adding or removing
wavelength converting material from transmissive element 174. In
one embodiment a red emitting phosphor 186 such as an alkaline
earth oxy silicon nitride covers a portion of transmissive element
174, and a yellow emitting phosphor 184 such as a YAG phosphor
covers another portion of transmissive element 174.
[0066] In another example, the adjustment of color point of light
emitted from the LED based illumination device may be accomplished
by adjusting electrical currents supplied to different LEDs of the
illumination device. In this manner, the color rendering index
(CRI), correlated color temperature (CCT), or any other relevant
color metric may be tuned based on the electrical currents supplied
to different LEDs of the illumination device. In one example, the
electrical currents are adjusted by primary ECB 120 as described
hereinbefore.
[0067] In some embodiments, the phosphors are mixed in a suitable
solvent medium with a binder and, optionally, a surfactant and a
plasticizer. The resulting mixture is deposited by any of spraying,
screen printing, blade coating, jetting, or other suitable means.
By choosing the shape and height of the transmissive element 174,
and selecting which portions of transmissive element 174 will be
covered with a particular phosphor or not, and by optimization of
the layer thickness and concentration of a phosphor layer on the
surfaces, the color point of the light emitted from the device can
be tuned as desired.
[0068] In one example, a single type of wavelength converting
material may be patterned on a portion of transmissive element 174.
By way of example, a red emitting phosphor 186 may be patterned on
different areas of the transmissive element 174 and a yellow
emitting phosphor 184 may be patterned on other areas of
transmissive element 174. In some examples, the areas may be
physically separated from one another. In some other examples, the
areas may be adjacent to one another. The coverage and/or
concentrations of the phosphors may be varied to produce different
color temperatures. It should be understood that the coverage area
of the red and/or the concentrations of the red and yellow
phosphors will need to vary to produce the desired color
temperatures if the light produced by the LEDs 162 varies. The
color performance of the LEDs 162, red phosphor and the yellow
phosphor may be measured and modified by any of adding or removing
phosphor material based on performance so that the final assembled
product produces the desired color temperature.
[0069] Transmissive element 174 may be constructed from a suitable
optically transmissive material (e.g., sapphire, quartz, alumina,
crown glass, polycarbonate, and other plastics). Transmissive
element 174 is spaced above the light emitting surface of LEDs 162
by a clearance distance. In some embodiments, this is desirable to
allow clearance for wire bond connections from the LED package
submount to the active area of the LED. In some embodiments, a
clearance of one millimeter or less is desirable to allow clearance
for wire bond connections. In some other embodiments, a clearance
of two hundred microns or less is desirable to enhance light
extraction from the LEDs 162.
[0070] In some other embodiments, the clearance distance may be
determined by the size of the LED 162. For example, the size of the
LED 162 may be characterized by the length dimension of any side of
a single, square shaped active die area. In some other examples,
the size of the LED 162 may be characterized by the length
dimension of any side of a rectangular shaped active die area. Some
LEDs 162 include many active die areas (e.g., LED arrays). In these
examples, the size of the LED 162 may be characterized by either
the size of any individual die or by the size of the entire array.
In some embodiments, the clearance should be less than the size of
the LED 162. In some embodiments, the clearance should be less than
twenty percent of the size of the LED 162. In some embodiments, the
clearance should be less than five percent of the size of the LED.
As the clearance is reduced, light extraction efficiency may be
improved, but output beam uniformity may also degrade.
[0071] In some other embodiments, it is desirable to attach
transmissive element 174 directly to the surface of the LED 162. In
this manner, the direct thermal contact between transmissive
element 174 and LEDs 162 promotes heat dissipation from LEDs 162.
In some other embodiments, the space between mounting board 164 and
transmissive element 174 may be filled with a solid encapsulate
material. By way of example, silicone may be used to fill the
space. In some other embodiments, the space may be filled with a
fluid to promote heat extraction from LEDs 162.
[0072] In the embodiment illustrated in FIG. 9, the surface of
patterned transmissive element 174 facing LEDs 162 is coupled to
LEDs 162 by an amount of flexible, optically translucent material
177. By way of non-limiting example, the flexible, optically
translucent material 177 may include an adhesive, an optically
clear silicone, a silicone loaded with reflective particles (e.g.,
titanium dioxide (TiO2), zinc oxide (ZnO), and barium sulfate
(BaSO4) particles, or a combination of these materials), a silicone
loaded with a wavelength converting material (e.g., phosphor
particles), a sintered PTFE material, etc. Such material may be
applied to couple transmissive element 174 to LEDs 162 in any of
the embodiments described herein.
[0073] In some embodiments, multiple, stacked transmissive layers
are employed. Each transmissive layer includes different wavelength
converting materials. For example, a transmissive layer including a
wavelength converting material may be placed over another
transmissive layer including a different wavelength converting
material. In this manner, the color point of light emitted from LED
based illumination device 100 may be tuned by replacing the
different transmissive layers independently to achieve a desired
color point. In some embodiments, the different transmissive layers
may be placed in contact with each other to promote light
extraction. In some other embodiments, the different transmissive
layers may be separated by a distance to promote cooling of the
transmissive layers. For example, airflow may by introduced through
the space to cool the transmissive layers.
[0074] The mounting board 164 provides electrical connections to
the attached LEDs 162 to a power supply (not shown). In one
embodiment, the LEDs 162 are packaged LEDs, such as the Luxeon
Rebel manufactured by Philips Lumileds Lighting. Other types of
packaged LEDs may also be used, such as those manufactured by OSRAM
(Ostar package), Luminus Devices (USA), Cree (USA), Nichia (Japan),
or Tridonic (Austria). As defined herein, a packaged LED is an
assembly of one or more LED die that contains electrical
connections, such as wire bond connections or stud bumps, and
possibly includes an optical element and thermal, mechanical, and
electrical interfaces. The LEDs 162 may include a lens over the LED
chips. Alternatively, LEDs without a lens may be used. LEDs without
lenses may include protective layers, which may include phosphors.
The phosphors can be applied as a dispersion in a binder, or
applied as a separate plate. Each LED 162 includes at least one LED
chip or die, which may be mounted on a submount. The LED chip
typically has a size about 1 mm by 1 mm by 0.5 mm, but these
dimensions may vary. In some embodiments, the LEDs 162 may include
multiple chips. The multiple chips can emit light similar or
different colors, e.g., red, green, and blue. The LEDs 162 may emit
polarized light or non-polarized light and LED based illumination
device 100 may use any combination of polarized or non-polarized
LEDs. In some embodiments, LEDs 162 emit either blue or UV light
because of the efficiency of LEDs emitting in these wavelength
ranges. In addition, different phosphor layers may be applied on
different chips on the same submount. The submount may be ceramic
or other appropriate material. The submount typically includes
electrical contact pads on a bottom surface that are coupled to
contacts on the mounting board 164. Alternatively, electrical bond
wires may be used to electrically connect the chips to a mounting
board. Along with electrical contact pads, the LEDs 162 may include
thermal contact areas on the bottom surface of the submount through
which heat generated by the LED chips can be extracted. The thermal
contact areas are coupled to heat spreading layers on the mounting
board 164. Heat spreading layers may be disposed on any of the top,
bottom, or intermediate layers of mounting board 164. Heat
spreading layers may be connected by vias that connect any of the
top, bottom, and intermediate heat spreading layers.
[0075] In some embodiments, the mounting board 164 conducts heat
generated by the LEDs 162 to the sides of the board 164 and the
bottom of the board 164. In one example, the bottom of mounting
board 164 may be thermally coupled to a heat sink, or a lighting
fixture and/or other mechanisms to dissipate the heat, such as a
fan. In some embodiments, the mounting board 164 conducts heat to a
heat sink thermally coupled to the top of the board 164. Mounting
board 164 may be an FR4 board, e.g., that is 0.5 mm thick, with
relatively thick copper layers, e.g., 30 micrometers to 100
micrometers, on the top and bottom surfaces that serve as thermal
contact areas. In other examples, the board 164 may be a metal core
printed circuit board (PCB) or a ceramic submount with appropriate
electrical connections. Other types of boards may be used, such as
those made of alumina (aluminum oxide in ceramic form), or aluminum
nitride (also in ceramic form).
[0076] Mounting board 164 includes electrical pads to which the
electrical pads on the LEDs 162 are connected. The electrical pads
are electrically connected by a metal, e.g., copper, trace to a
contact, to which a wire, bridge or other external electrical
source is connected. In some embodiments, the electrical pads may
be vias through the board 164 and the electrical connection is made
on the opposite side, i.e., the bottom, of the board. Mounting
board 164, as illustrated, is rectangular in dimension. LEDs 162
mounted to mounting board 164 may be arranged in different
configurations on rectangular mounting board 164. In one example
LEDs 162 are aligned in rows extending in the length dimension and
in columns extending in the width dimension of mounting board 164.
In another example, LEDs 162 are arranged in a hexagonally closely
packed structure. In such an arrangement each LED is equidistant
from each of its immediate neighbors. Such an arrangement is
desirable to increase the uniformity and efficiency of emitted
light.
[0077] FIGS. 13, 14, and 15 illustrate three exemplary luminaires.
Luminaire 350 illustrated in FIG. 13 includes an LED based
illumination device 300 with a rectangular form factor. The
luminaire 450 illustrated in FIG. 14 includes an LED based
illumination device 400 with a circular form factor. The luminaire
550 illustrated in FIG. 15 includes an LED based illumination
device 500 integrated into a retrofit lamp device. These examples
are for illustrative purposes. Examples of LED based illumination
devices of general polygonal and elliptical shapes may also be
contemplated.
[0078] Luminaires 350, 450, and 550 include LED based illumination
devices 300, 400, and 500, which may be similar to the LED based
illumination devices described above, reflectors 302, 402, and 502,
and light fixtures 301, 401, and 501, respectively. As depicted,
the light fixtures include a heat sink capability, and therefore
may be sometimes referred to as a heat sink. However, the light
fixtures may include other structural and decorative elements (not
shown). The reflectors are mounted to the LED based illumination
devices to collimate or deflect light emitted from each LED based
illumination device. Reflectors may be made from a thermally
conductive material, such as a material that includes aluminum or
copper and may be thermally coupled to each LED based illumination
device. Heat flows by conduction through the LED based illumination
device and the thermally conductive reflector. Heat also flows via
thermal convection over the reflector. Reflectors may be compound
parabolic concentrators, where the concentrator is constructed of
or coated with a highly reflecting material. Optical elements, such
as a diffuser or reflector may be removably coupled to an LED based
illumination device, e.g., by means of threads, a clamp, a
twist-lock mechanism, or other appropriate arrangement. As
illustrated in FIG. 15, the reflector 502 may include sidewalls 503
and a window 504 that are optionally coated, e.g., with a
wavelength converting material, diffusing material or any other
desired material.
[0079] As depicted in FIGS. 13, 14, and 15, the LED based
illumination device is mounted to a heat sink. The heat sink may be
made from a thermally conductive material, such as a material that
includes aluminum or copper and may be thermally coupled to an LED
based illumination device. Heat flows by conduction through an LED
based illumination device and the thermally conductive heat sink.
Heat also flows via thermal convection over the heat sink. Each LED
based illumination device may be attached to a heat sink by way of
screw threads to clamp the LED based illumination device to the
heat sink. To facilitate easy removal and replacement, the LED
based illumination device may be removably coupled to the heat
sink, e.g., by means of a clamp mechanism, a twist-lock mechanism,
or other appropriate arrangement. The LED based illumination device
includes at least one thermally conductive surface that is
thermally coupled to the heat sink, e.g., directly or using thermal
grease, thermal tape, thermal pads, or thermal epoxy. For adequate
cooling of the LEDs, a thermal contact area of at least 50 square
millimeters, but preferably 100 square millimeters should be used
per one watt of electrical energy flow into the LEDs on the board.
For example, in the case when 20 LEDs are used, a 1000 to 2000
square millimeter heat sink contact area should be used. Using a
larger heat sink may permit the LEDs to be driven at higher power,
and also allows for different heat sink designs. For example, some
designs may exhibit a cooling capacity that is less dependent on
the orientation of the heat sink. In addition, fans or other
solutions for forced cooling may be used to remove the heat from
the device. The bottom heat sink may include an aperture so that
electrical connections can be made to the LED based illumination
device.
[0080] Although certain specific embodiments are described above
for instructional purposes, the teachings of this patent document
have general applicability and are not limited to the specific
embodiments described above. Accordingly, various modifications,
adaptations, and combinations of various features of the described
embodiments can be practiced without departing from the scope of
the invention as set forth in the claims.
* * * * *